The present invention relates to a one-step process for simultaneously finish-stripping and dyeing synthetic fibers or synthetic fiber textile materials finished with mineral oil finishes, silicone oil finishes or both. This is accomplished by treating the fibers or textile materials with an aqueous liquor comprising as essential ingredients a) one or more surfactants selected from the group consisting of the anionic and amphoteric surfactants, b) one or more dyes and c) optionally one or more further compounds selected from the group consisting of the nonionic surfactants, the terpene hydrocarbons, the terpene alcohols and their esters with lower carboxylic acids, the sorbitol esters and their alkoxylates, the fatty acid ethanolamides, the alkylpolyglycosides and the solvents. This treatment is carried out in the pH range from 4.0 to 7.5, at final temperatures within the range of 80-110.degree. C. and at a liquor ratio of 5:1 to 100:1.
Examples of synthetic fibers which can be treated according to the present invention are polyamide fibers, e.g., nylon-6 (Perlon and others) or nylon-6,6, polyester fibers, polyurethane fibers and others known to one of ordinary skill in the art, and their blends with each or one another and their blends with other fibers of vegetable and animal origin. The process of the present invention relates more particularly to fibers composed of polyamides and composed of polyurethanes and to their blends with each or one another and their blends with fibers of vegetable and animal origin, particularly preferably fibers composed of polyamide, polyurethane or polyamide/polyurethane blends. Synthetic fiber textile materials are twisted or otherwise textile-mechanically treated yarns and knits or wovens made thereof. For some applications, for example for the manufacture of socks, combined yarns are used, comprising, for example, a polyurethane fiber and a crimped or uncrimped polyamide fiber.
To improve the processing properties of fibers and yarns produced therefrom, they are provided with a finish, which is then also present on textile materials produced therefrom. In the case of synthetic fibers, the finish is frequently a mineral oil or a silicone oil. However, these oily finishes interfere with the dyeing of fibers, yarns and textile materials through pronounced spotting. Therefore, a mineral oil or silicone oil finish has to be removed by a wash prior to the dyeing process. Such a prewash is known in principle and is carried out in known apparatus. The disadvantage of this separate wash is firstly the time required (about 80-90 min for a wash), the need for separate equipment for this purpose, the personnel required for this separate process, the production of large additional wastewater quantities, which have to be disposed of, and energy requirements for the heating and cooling in this separate operation. The dyeing process cannot be carried out until after the wash, and it has to be carried out with renewed expenditure in terms of the resources mentioned.